Quantitative Concept
biological availability
Subclass of:
Drug Kinetics
Definitions related to biological availability:
  • (bioavailability) How quickly and completely the body can absorb and use a nutrient.
    Harvard Dictionary of Health Terms
    Harvard Medical Publishing, 2011
  • (bioavailability) Rate and extent to which a drug is absorbed or is otherwise available to the treatment site in the body.
    CDISC Terminology
    Clinical Data Interchange Standards Consortium (CDISC), 2021
  • (bioavailability) The rate and extent to which the active ingredient or active moiety is absorbed from a drug product and becomes available at the site of action. For drug products that are not intended to be absorbed into the bloodstream, bioavailability may be assessed by measurements intended to reflect the rate and extent to which the active ingredient or active moiety becomes available at the site of action (21CFR320.1).
    NCI
    U.S. National Cancer Institute, 2021
  • The extent to which the active ingredient of a drug dosage form becomes available at the site of drug action or in a biological medium believed to reflect accessibility to a site of action.
    NLM Medical Subject Headings
    U.S. National Library of Medicine, 2025
  • Bioavailability refers to the extent and rate at which the active moiety (drug or metabolite) enters systemic circulation, thereby accessing the site of action.
    Merck Manuals
    Merck & Co., Inc., 2025
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This content should not be used in place of medically-reviewed decision support reference material or professional medical advice. Some terms may have alternate or updated definitions not reflected in this set. The definitions on this page should not be considered complete or up to date.